1. Field of the Disclosure
The present subject matter is generally directed to systems, methods, and tools for installing emergency slip hangers, and in particular for installing an emergency slip hanger and annular packoff assembly having a metal to metal sealing system in a wellhead without removing the blowout preventer from the wellhead.
2. Description of the Related Art
In a typical oil and gas drilling operation, wellhead are used to support the various casing strings that are run into the wellbore, to seal the annular spaces between the various casing strings, and to provide an interface with the blowout preventer (“BOP”), which is generally positioned at the top of the wellhead so as to control pressure while permitting drilling fluids to flow into and out of the wellbore. In most cases, the wellhead design is generally dependent upon many different factors, including the location of the wellhead and the specific characteristics of the well being drilled, such as size, depth, and the like.
In many drilling program, a plurality of substantially concentric casing strings of different sizes, such as two, three, four, or even more casing sizes, are generally run into the well so as to support the as-drilled wellbore, to facilitate the flow of drilling fluids into and out of the wellbore, and/or to isolate the wellbore from the various producing zones that may be present in the adjacent formations. Typically, a first outermost casing, sometimes referred to as a conductor casing, is fixed in the ground, and each successive inner casing is supported from the next adjacent outer casing by the use of specially designed mechanical supports, referred to as casing hangers. Casing hangers are generally made up of an external support or landing shoulder on the inner casing that lands on, or engages with, an internal support or load shoulder on the outer casing.
In many cases, the casing hangers that are used to support the various casing strings are often fixed in position on each individual casing string and positioned in the wellhead. In this way, the wellhead is used to support a number of casing hangers, each of which generally supports the weight of an individual casing string. However, in some cases, and for a variety of different reasons, an individual casing string may become stuck in as it is being run into the wellbore, in which case the fixed casing hanger that is located in the wellhead will not be in the proper position so as to support the casing string. Accordingly, if the casing string cannot be unstuck, it is often necessary to use an emergency slip-type casing support to support the casing string instead of the fixed position casing hanger located in the wellhead.
Emergency slip supports are tapered wedges that have a series of serrations or teeth that are configured to grip the casing string by biting into, i.e., locally indenting and/or deforming, the outside surface of the casing when the slip supports are subjected to an actuating force. Packing and/or sealing assemblies are then generally used to seal the annular space, or annulus, between the outside surface of the casing and the inside surface, or bore, of the wellhead so as to contain the wellbore pressure and to prevent hydrocarbons and/or other fluids from escaping to the environment. When the casing becomes stuck, i.e., such that it cannot be pulled out or pushed further down into the wellbore, the emergency slip hangers and the annular packing system are installed after the stuck casing has been cut and trimmed to an appropriate distance above the wellhead landing shoulder. However, due to the complexity and size of the tools that are often required to perform all of the various steps necessary to properly pack off and seal the annulus—activities which can frequently occur tens of meters or even more below the top of the wellhead—it is often necessary to remove the blowout preventer from the wellhead in order to provide sufficient access to properly perform the work, which can potentially reduce overall control of the drilled wellbore.
Furthermore, and in view of the fact that the emergency slip hangers and annular packoffs that are installed in such situations are intended to substantially be permanent repairs, the seals installed with the annular packoffs must remain reliable throughout the life of the wellhead, as they cannot readily be retrieved and replaced and/or maintained. Accordingly, it has become more and more common for the annular packoffs to utilize metal to metal seals, particularly in gas producing applications, as many elastomeric seals can leak under such conditions after an extended period of time in service.
Accordingly, there is a need to develop and implement new tools, systems, and methods that may be used to install an emergency slip hanger and annular packoff having a metal to metal sealing system in a wellhead through the BOP, that is, without removing the BOP from the wellhead.